Should vitamin D supplements be recommended to prevent chronic diseases?

Rapid Response:

Severe Enduring Mental Illnesses are also Chronic Diseases

Severe, enduring mental illnesses are also chronic diseases. In Meyer HE et al’s paper, they have considered evidence in reaching the recommendation that vitamin D supplementation is not recommended for the prevention of chronic disease. [1] This evidence pertained to cancer, cardiovascular diseases, myocardial infarction, cerebrovascular disorder, fractures, respiratory tract diseases, diabetes mellitus, and multiple sclerosis. However, evidence for the role of vitamin D in mental illness does exist but was not considered by this paper. These mental health conditions such as depression may be comorbid with the considered conditions [2] and are associated with poorer prognoses. [3] Consideration or acknowledgment of these may have conveyed the full ramifications and implications of Vitamin D deficiency and possibly affected their recommendations.

The World Health Organisation estimates that by 2020, mental illness, in particular depression would outstrip most other chronic diseases to become the second leading cause of Disability Adjusted Life Years (DALYs) lost. “Worldwide it will be second only to ischaemic heart disease for DALYs lost for both sexes. In the developed regions, depression will then be the highest ranking cause of burden of disease.” [4] Approximately 25% of prevalent depression is thought to be chronic in nature. [5] In the 2000 Global Burden of Disease study, Schizophrenia accounted for 1.1% of the total DALYs and 2.8% of Years Lived with Disability (YLDs). [4] Hence any associations of Vitamin D with mental disorders, where existent needs to be factored into public health recommendations.

Anglin et al’s systematic review and meta-analysis was indicative of an association between depression and low Vitamin D levels. [5] However, supplementation with Vitamin D did not significantly improve depression [6, 7]; but these studies had low numbers of participants. Low level of Vitamin D is now thought to be a risk factor for psychosis [8, 9].

We appreciate that limited resources ought to be well managed. However, we were disappointed that instead of stressing that bigger studies are urgently needed to clarify these associations, the authors chose to emphasize the absence of evidence for supplementation. Absence of evidence does not necessarily mean the non-existence of causality or association.